1. Field of the Invention
The present invention relates to an upper tool used to effect a press processing in a plate-shaped workpiece in cooperation with a lower tool.
2. Description of the Prior Art
Conventionally, in an upper tool mounted on a turret punch press for instance, a punch is housed in a cylindrical punch guide so as to be movable up and down. Further, the punch guide is formed of a metal, and a shock damping material such as urethane may be attached to the lower end surface of the punch guide. The shock damping material serves to reduce a noise generated during the punching processing.
In the conventional upper tool whose punch guide is formed of only a metal, since the punch guide is directly brought into contact with a plate-shaped workpiece, there exists a problem in that a noise is inevitably produced during punching processing, thus deteriorating the working environment markedly.
In the case where the shock damping material such as urethane is attached to the lower end surface of the punch guide, needle-shaped chips (refuse) produced during the punching processing may adhere onto the shock damping material. Thus, there exists another problem in that the plate-material may be scratched by the needle-shaped chips adhered to the shock damping material.